In case you didn't get this answered yet, conscription is 165, 255, or 347 days, that's 5½, 8½, or 11½ months.how long is it? I vaguely remember Ville Pokka doing this as well.
Depending on the mission and training and final rank. This is followed by periodic reservist training, until age 50 or 60, again depending on the task.
My understanding is that young pro athletes by default get the shortest 165 day term and they can serve it in a sports oriented unit, and they don't get the reservist call-ups. It's like the potential sports career is considered as a PR service rendered. I haven't looked at it that closely though.
Wikipedia has a tolerable piece on it in general, if you ignore some weird translations and the funny somewhat "look at me" criticisms at the tail end:
Conscription in Finland - Wikipedia